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NickQiZhuNickQiZhu
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create simple topojson albers usa recipe
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‎lib/topojson.js

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topojson = (function() {
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function merge(topology, arcs) {
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var fragmentByStart = {},
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fragmentByEnd = {};
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arcs.forEach(function(i) {
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var e = ends(i),
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start = e[0],
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end = e[1],
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f, g;
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if (f = fragmentByEnd[start]) {
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delete fragmentByEnd[f.end];
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f.push(i);
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f.end = end;
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if (g = fragmentByStart[end]) {
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delete fragmentByStart[g.start];
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var fg = g === f ? f : f.concat(g);
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fragmentByStart[fg.start = f.start] = fragmentByEnd[fg.end = g.end] = fg;
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} else if (g = fragmentByEnd[end]) {
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delete fragmentByStart[g.start];
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delete fragmentByEnd[g.end];
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var fg = f.concat(g.map(function(i) { return ~i; }).reverse());
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fragmentByStart[fg.start = f.start] = fragmentByEnd[fg.end = g.start] = fg;
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} else {
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fragmentByStart[f.start] = fragmentByEnd[f.end] = f;
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}
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} else if (f = fragmentByStart[end]) {
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delete fragmentByStart[f.start];
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f.unshift(i);
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f.start = start;
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if (g = fragmentByEnd[start]) {
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delete fragmentByEnd[g.end];
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var gf = g === f ? f : g.concat(f);
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fragmentByStart[gf.start = g.start] = fragmentByEnd[gf.end = f.end] = gf;
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} else if (g = fragmentByStart[start]) {
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delete fragmentByStart[g.start];
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delete fragmentByEnd[g.end];
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var gf = g.map(function(i) { return ~i; }).reverse().concat(f);
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fragmentByStart[gf.start = g.end] = fragmentByEnd[gf.end = f.end] = gf;
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} else {
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fragmentByStart[f.start] = fragmentByEnd[f.end] = f;
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}
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} else if (f = fragmentByStart[start]) {
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delete fragmentByStart[f.start];
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f.unshift(~i);
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f.start = end;
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if (g = fragmentByEnd[end]) {
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delete fragmentByEnd[g.end];
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var gf = g === f ? f : g.concat(f);
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fragmentByStart[gf.start = g.start] = fragmentByEnd[gf.end = f.end] = gf;
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} else if (g = fragmentByStart[end]) {
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delete fragmentByStart[g.start];
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delete fragmentByEnd[g.end];
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var gf = g.map(function(i) { return ~i; }).reverse().concat(f);
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fragmentByStart[gf.start = g.end] = fragmentByEnd[gf.end = f.end] = gf;
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} else {
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fragmentByStart[f.start] = fragmentByEnd[f.end] = f;
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}
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} else if (f = fragmentByEnd[end]) {
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delete fragmentByEnd[f.end];
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f.push(~i);
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f.end = start;
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if (g = fragmentByEnd[start]) {
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delete fragmentByStart[g.start];
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var fg = g === f ? f : f.concat(g);
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fragmentByStart[fg.start = f.start] = fragmentByEnd[fg.end = g.end] = fg;
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} else if (g = fragmentByStart[start]) {
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delete fragmentByStart[g.start];
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delete fragmentByEnd[g.end];
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var fg = f.concat(g.map(function(i) { return ~i; }).reverse());
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fragmentByStart[fg.start = f.start] = fragmentByEnd[fg.end = g.start] = fg;
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} else {
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fragmentByStart[f.start] = fragmentByEnd[f.end] = f;
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}
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} else {
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f = [i];
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fragmentByStart[f.start = start] = fragmentByEnd[f.end = end] = f;
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}
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});
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function ends(i) {
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var arc = topology.arcs[i], p0 = arc[0], p1 = [0, 0];
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arc.forEach(function(dp) { p1[0] += dp[0], p1[1] += dp[1]; });
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return [p0, p1];
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}
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var fragments = [];
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for (var k in fragmentByEnd) fragments.push(fragmentByEnd[k]);
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return fragments;
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}
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function mesh(topology, o, filter) {
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var arcs = [];
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if (arguments.length > 1) {
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var geomsByArc = [],
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geom;
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function arc(i) {
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if (i < 0) i = ~i;
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(geomsByArc[i] || (geomsByArc[i] = [])).push(geom);
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}
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function line(arcs) {
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arcs.forEach(arc);
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}
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function polygon(arcs) {
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arcs.forEach(line);
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}
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function geometry(o) {
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if (o.type === "GeometryCollection") o.geometries.forEach(geometry);
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else if (o.type in geometryType) {
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geom = o;
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geometryType[o.type](o.arcs);
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}
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}
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var geometryType = {
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LineString: line,
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MultiLineString: polygon,
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Polygon: polygon,
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MultiPolygon: function(arcs) { arcs.forEach(polygon); }
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};
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geometry(o);
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geomsByArc.forEach(arguments.length < 3
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? function(geoms, i) { arcs.push(i); }
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: function(geoms, i) { if (filter(geoms[0], geoms[geoms.length - 1])) arcs.push(i); });
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} else {
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for (var i = 0, n = topology.arcs.length; i < n; ++i) arcs.push(i);
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}
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return object(topology, {type: "MultiLineString", arcs: merge(topology, arcs)});
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}
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function featureOrCollection(topology, o) {
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return o.type === "GeometryCollection" ? {
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type: "FeatureCollection",
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features: o.geometries.map(function(o) { return feature(topology, o); })
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} : feature(topology, o);
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}
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function feature(topology, o) {
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var f = {
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type: "Feature",
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id: o.id,
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properties: o.properties || {},
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geometry: object(topology, o)
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};
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if (o.id == null) delete f.id;
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return f;
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}
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function object(topology, o) {
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var tf = topology.transform,
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kx = tf.scale[0],
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ky = tf.scale[1],
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dx = tf.translate[0],
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dy = tf.translate[1],
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arcs = topology.arcs;
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function arc(i, points) {
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if (points.length) points.pop();
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for (var a = arcs[i < 0 ? ~i : i], k = 0, n = a.length, x = 0, y = 0, p; k < n; ++k) points.push([
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(x += (p = a[k])[0]) * kx + dx,
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(y += p[1]) * ky + dy
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]);
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if (i < 0) reverse(points, n);
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}
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function point(coordinates) {
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return [coordinates[0] * kx + dx, coordinates[1] * ky + dy];
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}
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function line(arcs) {
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var points = [];
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for (var i = 0, n = arcs.length; i < n; ++i) arc(arcs[i], points);
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if (points.length < 2) points.push(points[0].slice());
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return points;
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}
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function ring(arcs) {
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var points = line(arcs);
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while (points.length < 4) points.push(points[0].slice());
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return points;
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}
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function polygon(arcs) {
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return arcs.map(ring);
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}
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function geometry(o) {
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var t = o.type;
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return t === "GeometryCollection" ? {type: t, geometries: o.geometries.map(geometry)}
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: t in geometryType ? {type: t, coordinates: geometryType[t](o)}
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: null;
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}
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var geometryType = {
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Point: function(o) { return point(o.coordinates); },
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MultiPoint: function(o) { return o.coordinates.map(point); },
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LineString: function(o) { return line(o.arcs); },
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MultiLineString: function(o) { return o.arcs.map(line); },
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Polygon: function(o) { return polygon(o.arcs); },
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MultiPolygon: function(o) { return o.arcs.map(polygon); }
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};
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return geometry(o);
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}
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function reverse(array, n) {
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var t, j = array.length, i = j - n; while (i < --j) t = array[i], array[i++] = array[j], array[j] = t;
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}
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function bisect(a, x) {
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var lo = 0, hi = a.length;
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while (lo < hi) {
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var mid = lo + hi >>> 1;
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if (a[mid] < x) lo = mid + 1;
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else hi = mid;
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}
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return lo;
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}
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function neighbors(objects) {
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var indexesByArc = {}, // arc index -> array of object indexes
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neighbors = objects.map(function() { return []; });
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function line(arcs, i) {
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arcs.forEach(function(a) {
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if (a < 0) a = ~a;
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var o = indexesByArc[a];
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if (o) o.push(i);
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else indexesByArc[a] = [i];
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});
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}
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function polygon(arcs, i) {
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arcs.forEach(function(arc) { line(arc, i); });
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}
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function geometry(o, i) {
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if (o.type === "GeometryCollection") o.geometries.forEach(function(o) { geometry(o, i); });
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else if (o.type in geometryType) geometryType[o.type](o.arcs, i);
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}
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var geometryType = {
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LineString: line,
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MultiLineString: polygon,
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Polygon: polygon,
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MultiPolygon: function(arcs, i) { arcs.forEach(function(arc) { polygon(arc, i); }); }
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};
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objects.forEach(geometry);
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for (var i in indexesByArc) {
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for (var indexes = indexesByArc[i], m = indexes.length, j = 0; j < m; ++j) {
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for (var k = j + 1; k < m; ++k) {
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var ij = indexes[j], ik = indexes[k], n;
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if ((n = neighbors[ij])[i = bisect(n, ik)] !== ik) n.splice(i, 0, ik);
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if ((n = neighbors[ik])[i = bisect(n, ij)] !== ij) n.splice(i, 0, ij);
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}
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}
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}
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return neighbors;
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}
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return {
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version: "1.2.3",
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mesh: mesh,
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feature: featureOrCollection,
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neighbors: neighbors
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};
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})();

‎src/chapter12/usa.html

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<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<meta name="viewport" content="initial-scale=1,maximum-scale=1"/>
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<title>Albers USA with TopoJSON</title>
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<link rel="stylesheet" type="text/css" href="../../css/styles.css"/>
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<script type="text/javascript" src="../../lib/d3.js"></script>
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<script type="text/javascript" src="../../lib/topojson.js"></script>
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<style>
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path {
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fill: #ccc;
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stroke: #fff;
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stroke-width: .5px;
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}
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path:hover {
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fill: red;
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}
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</style>
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</head>
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<body>
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<script type="text/javascript">
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var width = 960,
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height = 500;
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var path = d3.geo.path();
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var svg = d3.select("body").append("svg")
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.attr("width", width)
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.attr("height", height)
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.append('g')
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.call(
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d3.behavior.zoom()
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.scaleExtent([1, 10])
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.on("zoom", zoom)
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);
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d3.json("/data/us.json", function (error, topology) {
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svg.selectAll("path")
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.data(topojson.feature(topology, topology.objects.counties).features)
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.enter().append("path")
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.attr("d", path);
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});
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function zoom() {
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svg.attr("transform", "translate("
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+ d3.event.translate
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+ ")scale(" + d3.event.scale + ")");
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}
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</script>
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</body>
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</html>

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